Classification of executive mechanisms depending on character of static moment of resistance (Ms)

Even with the greatest simplification considering the transient processes (neglecting of electromagnetic and thermal regimes), when only an electromechanical transient process is taken into account, the system of differential equations is considered, where equations of voltage equilibrium and equation of motion are included in.

In such a way, the equation of motion is one of two main equations, that describe the passing of transient process, and its component, which essentially influence on character of motion, is static resistance moment, which is different for various executional mechanisms.

The main factors, from which the magnitude of depends, are speed, path, time, features of executional mechanism technological process.

In dependence of character of all executional mechanisms can be conditionally divided into 5 classes.

1-st class. This class includes executional mechanisms with constant static moment

,

such as load lifting mechanisms, rolling mills, loading-offloading operations, planning machines.

2-nd class. This class includes executional mechanisms, where depends on speed v

M_s=f( v ).

This dependence can be insignificant, or significant, linear, or non-linear. Moment can depend on speed with degree 0-2, and for high-speed machines – even 3-4. This class includes mechanisms with ventilator characteristic (centrifugal pumps, ventilators, compressors, centrifuge, screw propeller, machine-tools).

3-rd class. This class includes mechanisms, where depends on path (on angle of rotation in rotating drives)

,

these are executional mechanisms in mechanical part of which such transforming links are present, as crank-lever, eccentric, link gear, camshaft mechanisms and so on (scissors, presses, turners, jaw crushers, reciprocating and other machines). For the most of such executional mechanisms function is difficult to set analytically, so it is set graphically.

4-th class. This class includes mechanisms, of which simultaneously depends on speed and path

M_s=f ( v, ),

such as railway transport (electric locomotives, diesel locomotives, trams), drive of draw bridge, drive of pilot devices and so on. For example, the motion of railway carriage under the angle or on curves. Here dependence on speed – friction in axes, friction on railways, and dependence on path – motion by slopes, motion on angles and so on.

5-th class. This class includes mechanisms, static resistance moment of which is the function of time

,

such as that operating under the disturbance force, which is changed in time by periodic law, or follower drive. Such class includes executional mechanisms, where depends on time taking into account properties of processed material, or character of technological process. Disturbance force with this has casual character (ball mills, combine machines, grinding machines, crushers and so on).

Дата добавления: 2014-01-05